ABSTRACT The proposed intervention, Culturally Responsible Stress Reduction: A Mobile Mindfulness Application to Support Health Promotion for African Americans (CRSR), is designed to encourage the use of mindfulness to mitigate the disproportionate amount of stress-related health disparities facing African Americans. Current mindfulness approaches have been unsuccessful in engaging this population. This proposal aims to bridge this disparity by developing an mHealth (mobile health) mindfulness application (?app?) tailored specifically to the cultural values of the African American community. Mindfulness involves meditative practices that cultivate purposeful and nonjudgmental attention to current thoughts, emotions, and physical sensations in the body. Mindfulness has been incorporated into widely-used interventions, including Acceptance and Commitment Therapy (ACT). The CRSR app will be grounded in ACT and will integrate the convenience of mobile technology with tailored content to allow users to shift from potentially harmful culturally prescribed stress-coping activities (e.g., self-reliance, emotional suppression) to adaptive mindfulness-based stress-coping activities aligned with culturally specific values. This integration of content, backed by theory and empirical evidence, effective instructional delivery, an interdisciplinary development team, and modern communication technology will produce an effective mHealth intervention. The CRSR app features include guided meditations to connect the user to the present moment and a place of calm through culturally aligned exercises grounded in spirituality, orality, self-empowerment, and resilience; personalized notifications prompting users to reflect and engage with the app; periodic email messages on the importance mindfulness as a way increase control over physical and psychological health; and user- customized reminders. Phase I included developing a testable prototype of the CRSR app, called Mindful You. The prototype provided functionality for participants to practice mindfulness and was used to test proof of concept, i.e., the feasibility and social acceptability of the CRSR app. Users experienced significantly decreased stress and increased self-efficacy. They also reported increased use of mindfulness behaviors and improved self- regulation. Phase II will iteratively build on the prototype to develop the final product and test its efficacy with a fully-powered randomized controlled trial. The final product will consist of a native mobile application on Android and Apple iOS. The applicant, Trifoia, has assembled a knowledgeable and experienced team of research scientists, content and technology developers, and evaluation specialists to adequately realize this project. The company has an established track record of developing and marketing technology-assisted public health interventions.